Schedule II - Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Other income									$ 538	$ 673	$ 853
Total revenues	$ 225,105	$ 219,870	$ 220,112	$ 212,972	$ 203,575	$ 201,726	$ 199,525	$ 181,046	878,059	785,872	651,039
Expenses:
General and administrative expenses									105,686	100,118	87,821
Interest expense									12,795	12,377	12,125
Other expense									16,151
Total expenses									820,428	718,754	619,710
Loss before federal income taxes									57,631	67,118	31,329
Federal income tax benefit									12,137	13,389	38,233
Net loss from continuing operations before equity in undistributed net income (losses) of subsidiaries	14,742	8,361	8,696	13,695	13,464	15,603	14,652	10,010	45,494	53,729	(6,904)
Net income (loss)	$ 8,520	$ 8,312	$ 8,618	$ 13,440	$ 14,120	$ 15,174	$ 14,454	$ 10,795	38,890	54,543	(43,993)
Parent Company | Reportable Legal Entities
Revenues:
Other income									33	165	630
Total revenues									33	165	630
Expenses:
General and administrative expenses									714	5,325	13,461
Write-off of amounts related to sale of affiliate										650	10,622
Intercompany interest expense (income)									18	(27)	(29)
Interest expense									12,795	12,377	12,125
Other expense									8,164
Total expenses									21,691	18,325	36,179
Loss before federal income taxes									(21,658)	(18,160)	(35,549)
Federal income tax benefit									4,669	3,284	8,341
Net loss from continuing operations before equity in undistributed net income (losses) of subsidiaries									(16,989)	(14,876)	(27,208)
Equity in undistributed net income (losses) of subsidiaries, net of tax									55,879	69,419	(16,785)
Net income (loss)									$ 38,890	$ 54,543	$ (43,993)